NOT TO BE TAKEN FROM THIS ROOM
SEASONAL DRIFT IN CARBOHYDRATE CONCEN¬
TRATIONS IN GROWING BARLEY
J. Kastelic
Department of Flant Science
University of Alberta
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SEASONAL DRIFT IN CARBOHYDRATE CONCEN¬
TRATIONS IN GROWING BARLEY
J. Kastelic
Department of Plant Science
A THESIS
submitted to the University of Alberta
in partial fulfilment of the
requirements for the degree of
MASTER OF SCIENCE
Edmonton, Alberta
April, 1945
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TABLE OF CONTENTS
• \
Page
Introduction . 1
Review of Literature . 3
Materials and Methods.«. IS
Materials . IS
Method of collection .. 13
Preparation of material . 14
Method of analysis ...* 17
Technique used in estimation of sugars S3
Experimental Results . S4
Seasonal drift in sugar and dry matter
content . S4
Discussion and Summary . 61
Acknowledgements .. 67
References . 68
nr 3 • re r f£l
SEASONAL DRIFT IN CARBOHYDRATE CONCEN¬
TRATIONS IN GROWING BARLEY
J. Kastelic
INTRODUCTION
Since the potential supply of raw fructose in the
form of inulins and fructosans is now known to he enormous,
attention has been directed towards possibilities of commer¬
cial utilization. If fructose were to become available in
large quantities at the same price as sucrose, its distinctive
properties should earn for it a permanent place on the carbo¬
hydrate market. It is the sweetest and most soluble of all
sugars. Its presence in syrups prevents the crystallization
of the other sugars present and, in contrast to sucrose which
is subject to inversion change, its flavor is permanent. It
is also in demand as an ingredient of medicinal preparations.
Economic and technological barriers have prevented
the development of a fructose industry in the past. There is,
however, reason to believe that the technological difficulties
have been largely overcome. At the Iowa State College and at
the University of Illinois processes for manufacturing fructose
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from the tubers of Jerusalem Artichokes have been in success¬
ful pilot scale operation for a number of years.
It should be emphasized that the economic feasibility
of a fructose industry in Canada must be left in doubt until
sufficient over-all data on yield and a comprehensive survey
of sources of raw fructosans become available. It may also
be pointed out that the effect of soil and weather conditions
on the fructosan accumulation in plants is at present not too
well understood. While the occurrence of fructosans and their
importance in the general carbohydrate metabolism in plants
have received a great deal of attention from a number of
biochemists at the Royal Institute of Technology in G-reat
Britain, no attempt has been made to investigate commercial
possibilities of using fructosans as raw material for a fruc¬
tose industry. From the conclusions reached by fructosan
chemists, it would appear, on the surface at least, that the
accumulation of fructosans in plants is the result of many and
probably complex factors.
Nevertheless, certain analytical results obtained
in the biochemical study of rye, wheat, and barley indicate
some possibility of finding cereal and forage crops suitable
for commercial production of fructose. Norman (13) in Great
Britain reported in 1936 that the fructosan constituted 34 fo
of the oven dry weight of the above-ground portions of rye
grass after about six weeks of growth. Since fructose aris¬
ing from sucrose was included in his estimate this value
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would appear to be much, too high. This has been shown in
subsequent investigations by others (4). Notwithstanding the
failure to confirm Norman*s results there remains some pos¬
sibility of finding relatively high concentrations of fruc-
tosans in certain plants grown under conditions which promote
the storage of this sugar.
The investigation contained in this report was
undertaken as a preliminary survey of the effect of some of
the factors which influence the fructose and fructosan con¬
tent of barley grown under field conditions.
REVIEW OF LITERATURE
A detailed review of the fructosans in monocoty¬
ledons can be obtained by referring to Archbold (4). It is
stated that the earliest study on this compound was made by
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Kuhnemann (1875), Munstz (1878-1886), and Ludwig and Muller
(1873). The discovery of fructosan in cereals resulted from
the attempts of agricultural chemists to isolate dextrins as
intermediate products between sugar and starch during the
development of the grain. So much controversy arose at this
time as to the presence or absence of dextrins in monocoty¬
ledons that little if any significance was given to the
discovery of the fructose polymer. While a number of attempts
were made to prepare a pure fructosan from plant extracts, the
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methods in use at that time led to isolation of more or less
impure substances. This resulted in a variety of descriptions
of the compound so that even to this day the nomenclature of
these carbohydrates is far from satisfactory.
The more modern work, especially that by Augem (1938),
Belval (1934, 1933, 1939), Colin and Chaudin (1933), Challinor
et al (4); Norman (1936) (14); Archbold (1938) (3); and Bar-
nell (1938) (10), has confirmed the presence of fructosans in
the plants examined by the early workers. It is now well
established that the fructosans are usually found as one of
the soluble sugars in the cereals and forage crop plants, and
that they may form an appreciable part of the total sugar at
certain stages during growth.
There still remains a great deal of research to be
done on the chemistry of the fructosan molecules, but it is
now generally accepted that they yield only fructose on acid
or invertase hydrolysis and that their chemical constitution
may differ slightly according to the source. Full details of
their chemistry properly belong to the field of pure chemistry
and may be obtained from the original papers of Hibbert et al
and Challinore et al (4), Haworth et al (13), and Reich, W.S.
(15).
It has been only in relatively recent years that
satisfactory methods for the quantitative estimations of
fructosans have been developed and almost without exception
all of the work has been done by investigators at the Research
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Institute of Plant Physiology, Imperial College of Science
and Technology, London. The earlier work was done in France
and Germany, and in the literature reviewed no reference to
fructosan is reported in any of the work on plant sugars
carried out on this continent*
From the available information it can be stated
that the amounts of fructosan found in the several plants
studied vary within wide limits and are subject to the same
marked seasonal changes and environmental conditions that
affect the other sugars. In a series of investigations by
Colin and Belval (4) on the changes in sugar concentrations in
stems and heads of cereals it was observed that, as the spike
emerged, fructosans began to accumulate in the stems and the
concentration reached a maximum when full growth of the plant
was reached. In wheat stems the value reached was 5.08$ and
at the onset of head formation the heads contained 6 to 8$ of
the fresh weight. No fructosans were found in the leaves.
Archbold^ and Barter f s (6) successful isolation of
fructosans from barley leaves reopened the question of the
significance of fructosans in carbohydrate metabolism and
marked the real beginning of detailed study of the role they
play. By 1940 Archbold (4) had firmly established that fruc¬
tosans may be distributed throughout the whole plant.
Earlier workers, notably Colin and Belval (4)
supported the view that stored sugars, including fructosans,
were stored during the early stages of the plant*s growth and
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that these reserve stores of sugar were drawn upon when the
heads began to develop♦ Barnell (9) (10), working with wheat
and Archbold (3) (5), working with barley, confirmed Colin and
Belval’s (4) results on the seasonal drift of sugar concentra¬
tions. When, however, their results were examined on the
basis of quantity per plant, it became clearly evident that
the stored sugars were not available in the sense that they
can be used as substrates for further growth at a site distant
from that at which they originally accumulate. Archbold (3)
(5), Archbold and Mukerjee (8), and Archbold and Datta (7)
observed that storage of sugar and fructosan was simply a
balance of supply over demand and that the sudden onset of the
large loss of these sugars from the plant tissues associated
with the development of the heads is unrelated. The head is
therefore entirely dependent on primary assimilate translocated
to it or produced in situ and immediately and irreversibly
synthesized.
A consideration of results of the investigations of
Archbold et al leads to the conclusion that only conditions
which promote the production of primary assimilates by green
parts of the plant in excess of immediate growth requirements
will result in storage of sugars. It is also to be noted
that conditions which promote sugar storage result also in
the production of relatively large amounts of fructosan.
Losses from the plant after the maximum is reached are
related to levels of concentrations reached.
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It has been observed by Archbold (3) and Russell
(17) that mineral deficiencies have rather marked effect on
the amounts of sugars stored* An indication of what was ob¬
served when barley was grown under conditions of mineral
deficiencies (taken from Archbold’s and Russell’s work)
appears in the following tables:
TABLE A
Total sugar and fructosan content of barley
plants grown in sand and receiving
nitrogen-deficient dressings
% fresh weight
Leaves
Stems
Heads
Control -N
Control -N
Control
-N
Total sugar
1.58 3.04
2.03 5.76
4.79
4.81
Fructosan
0.13 1.15
0.43 4.03
2.22
2.47
TABLE B
Mean effect of potassium and phosphorus
deficiency and of sodium-calcium
balance on fructosan
concentration in
barley
Potassium
Phosphorus
Sodium/calcium balance
Leaves
Stems
Leaves
Stems
Leaves
Stems
High
0.93
2.02
High
0.28
0.86
High Na 0.45
1.01
Medium
Low
0.53
0.18
1.19
0.24
Low
1.82
1.44
High Ca 0.65
1.29
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Gregory (12), in an extensive study of mineral
nutrition of plants found that nitrogen deficiency had no con¬
sistent effect on reducing sugars but that the total carbohy¬
drate was greatly increased. The effect of phosphorus
deficiency resulted in higher levels of free reducing sugars
but total sugar was less affected; while potassium deficiency
lowers both free reducing sugar and total sugar.
Richards (16) investigating a similar problem, found
evidence* supporting Gregory’s observations and confirmed the
fact that the various mineral treatments affected the ratio
of sucrose to reducing sugars. Finally, Russell (17) found
ratios of fructosan to other sugars greatly influenced by the
various conditions of mineral deficiency, and that in the
final analysis the fructosan accumulation was controlled
almost wholly by the concentration of other sugars.
On the basis of experiments on mineral deficiencies
it becomes clear that fructosans accumulate under all condi¬
tions promoting storage of sugars.
The studies on carbohydrate content of plants grow¬
ing under field conditions is confined almost entirely to the
observations Barnell (9) (10) made on wheat. Two wheat
varieties were selected and planted in the fall, and harvested
* No consistent differences ascribable to potassium were
found.
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the following summer. The percentage of sucrose in the plants
was found to some extent to be a function of temperature, the
sucrose value increasing with low temperature and falling
with moderate temperature. During one cold period sucrose
rose from a value of ,25$ of the fresh weight to a peak, 17
days later, of 1,55%. The low temperatures were associated
with more than average sun so that, under frost conditions, the
rise in sucrose concentration may be due, to some extent at
least, to the rate of production of sucrose by photosynthesis
exceeding the rate of utilization in the growth and respira¬
tion processes. Temperature conditions resulted in greater
fluctuations of sucrose content than did hours of sunshine
when results were analyzed statistically. Barnell (10) con¬
sidered sucrose to be the dominant sugar and, except in the
later stages of growth when the highest value for total sugar
was observed, glucose exceeded fructose. The values obtained
by him are as follows:
Maximum Values of Fructose, Glucose, and Sucrose (% of fresh
weigFtTT3' j-- ---
Time of head emergence maximum Glucose - .50%
Two weeks later " Sucrose - 5 to 4%
At same time or a
little later " Fructose exceeds glucose
until harvest.
No significant differences were found in sugar con¬
centrations of the two wheat varieties except that in the
later variety the maximum values were reached later. Barnell
9
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finally suggests that the sugar stored is not essential to
filling of the grain, and thus supports the conclusions ad¬
vanced by Archbold and others*
No reference to daily variations of fructosans is
reported in the literature reviewed* While the work of Curtis
is included in the references of this report it must be under¬
stood that no attempt to estimate the fructosans was made by
him. Curtis (11) observed that the sugar content of alfalfa
is greatly influenced by the time of day at which it is cut*
The observed results indicate differences between afternoon
and morning cuttings are of the order of 83$ or, in some
cases, more* These differences were estimated to fall almost
entirely on the soluble fractions of the plant materials and
would therefore include all the sugars. Curtis further
suggests, on the basis of observations made on carbohydrate
losses during "curing”, that losses of soluble sugars may
reach proportions of 50$ of the amount known to exist in the
green material. Woodward, Tisdale, and Shepherd (EO) disagree
with Curtis, stating that such high losses cannot be real,
since losses due to respiration could not account for such
large amounts of sugar* It has already been pointed out,
nevertheless, in references to the work of Archbold and
others, that losses of sugar from plant tissues have been
observed to be large*
It would seem from the foregoing that there is a need
for more evidence from experiments with plants to determine
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more exactly the magnitude of these changes as related to
time factors, soil, and weather effects, and kind of crop
concerned.
At present, only the all-over quantitative changes
in sugar concentrations appear to be known. Archbold and
Datta (7), in their more recent work, have concluded that,
before much more can be known of the distribution of the car¬
bohydrate supply for either growth processes or storage,
nitrogen metabolism must be considered in relation to carbo¬
hydrate synthesis and utilization. This view is further
borne out by work of Richards (16) who demonstrated that a
remarkably close relationship exists between respiration rate
and protein content.
It may be of interest to note that Archbold is now
engaged in experiments on the part played by nitrogen in
determining the distribution of the available carbohydrate
supply.
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- 12
MATERIALS AND METHODS
Materials
The barley used in these experiments was grown from
foundation stock seed of Newal at the University of Alberta.
Replicate seedings were made on May 3, May 17, May 25, June 3,
and June 22*
Each of the first seedings consisted of one 40-foot
row. This material was used in the preliminary testing of
methods of analysis. The final planting consisted of 24
rows, 50 feet long and spaced nine inches apart. Plants from
this seeding were used for most of the analytical work reported
in this paper.
The barley was planted on a field of black loam
which had been summerfallowed the previous year* The field is
typical of the agricultural soils in the Edmonton area and
considered to be very fertile.
The period from June 22 to September 30 was excep¬
tionally wet and very vigorous growth of the barley occurred.
Lodging occurred at the end of July after considerable wet
weather. The barley was fully headed 57 days after planting,
at which time it was approximately 42 inches high. The last
collection was made 100 days after planting. The late sowing
and abnormally high rainfall contributed to late maturity, so
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-13 -
that even at the end of 100 days many tillers had not
ripened, although the growth period for Newal grown at Edmon¬
ton, on the basis of a seven-year average, is 88 to 90 days.
Method of Collection
At weekly intervals, beginning on the eighth day
after planting and ending after 100 days of growth, single
plants selected at random over the whole plot were cut with
shears at ground level until 25 to 150 plants were obtained.
To measure the effect of time of collection, one collection
was made at 4:30 in the afternoon and another at 8:30 the fol¬
lowing morning.
The whole plants were immediately brought to the
laboratory where they were cut into half-inch lengths and
thoroughly mixed. A forty-gram sample was weighed out and
placed in 200 cc. of boiling 80$ alcohol. Ten to twenty grams
for moisture content determinations were placed in a drying
oven kept at 75 to 80°C. The remainder was placed in large,
shallow pans and allowed to dry at room temperature. This
material, when thoroughly dry, was ground in a Wylie mill and
placed in jars until required.
Beginning on August 18, weekly analyses for various
carbohydrates were made on the component parts of the plants
collected at 4:30 p.m. Heads were separated at the junction
with the peduncle, leaves detached at the junction with sheaths
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- 14 -
and sheaths peeled from the stems. After separation—which
was done as quickly as possible—the various parts of the
plants were cut up. Mixed portions of 5 to 10 grams were
weighed out and placed in boiling 80$ alcohol.
Notes on height of plants and stage of development,
together with notes on weather conditions at the time of
collection, were taken throughout the growth period. Detailed
records on weather for the entire period appear elsewhere in
this report.
Preparation of Material
As a rule a 40-gram sample of the freshly collected
and cut material was placed in 200 cc. of boiling 80$ alcohol
to prevent enzymatic hydrolysis of fructosans and sucrose.
Since fructosans are not extracted by alcohol, a water
extraction was carried out on the material which was first
freed from alcohol. The alcohol was poured off and the plant
material washed free of alcohol by shaking with several addi¬
tions of water. The residual material was transferred to a
Waring Blendor, sufficient water added to cover the material,
and cutting in the blendor was carried out for approximately
five minutes. It was observed that the material was reduced
to a very finely divided condition. After transfer to a
wide mouth Erlenmeyer, the cut material was shaken in a
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15 -
mechanical shaker for approximately two hours * The result¬
ing water extract was transferred to a graduated flask to
which the residue of the alcoholic extract and washings were
added after the alcohol had been removed by distillation under
reduced pressure. The residual material was then washed by
shaking with small additions of water and decantation of the
washings into the flask until the required volume was nearly
attained. The liquid was finally made up to volume and pre¬
served by the addition of a little toluene. The extracts
obtained from the young material were always deeply colored
by the pigments extracted during water and alcohol treatments.
Older plants, especially near the end of the growth season,
did not give such highly colored extracts.
When analyses were mad© on the dried materials the
same procedures were used, except for the weight of material
and final volume of extract.
Residues after alcoholic and water extractions were
re-extracted and in no case was there an appreciable amount of
total sugar remaining in the residue, and the amount which did
remain was of the same order for different samples.
Results of some of such re-extractions are shown in
Table C
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- 16 -
TABLE C
Total sugar content in water extracts of barley
Age (days)
1st extraction
2nd extraction
Green plants
($ of green weight)
8
1.22
.03
29
1.46
.03
54
2.83
.04
Dried plants
(% of dry weight)
21
3.76
.16
35
2.12
.15
49
8.38
.15
63
11.29
.15
77
6.32
.09
91
1.31
.13
* Removal of alcohol from the alcohol extract and
washings presented many difficulties when lack of pressure in
water taps made the use of water aspirators unreliable. This
was finally satisfactorily overcome by using a vacuum pump on
a system consisting of two HgO condensers, a Claissen flask,
and a large CaClg trap. Continual use of the pump over
periods of a month or more revealed little dilution of oil in
the pump. When the vapor of the alcohol and water solution
was pumped off at 2 to 3 cm. of mercury, reduction in volume
of some 200 to 300 cc. was possible in three hours or less.
A fine capillary tub© was used to admit small bubbles of air
into the solution during progress of distillation in order to
prevent frothing and bumping.
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- 17 -
The moisture and dry weight determinations were dif¬
ficult to make accurately because of the rainy conditions
that prevailed during periods of collection. Plants col¬
lected in the morning were, with few exceptions, either
covered with heavy dew or else with rain which had fallen
during the night. No attempt was made to dry off excess
moisture before sampling, since it was essential that analysis
be made on the plants as soon after collection as possible.
Any large drops of surplus moisture on the plants were merely
shaken off.
Considerable error may arise from this source and,
in any future work, some attempt should be made to overcome
this difficulty.
Methods of Analysis
A. Reducing Sugars
The modified Harding and Downs copper reduction
method was used in all estimations of reducing sugars.
Separate estimates of fructose were made after oxidation of
the glucose by hypoiodate. Both procedures are described
fully by Van der Plank (19).
Values for reducing sugars in terms of standard .01
Normal sodium thiosulphate were obtained by using various con¬
centrations of chemically pure fructose and glucose, and
. ■. . : . 1 . : - : ' • . - ■: ‘ • ’
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- 18 -
plotting the results on a graph. These values were used to
estimate the reducing power of the plant extracts. Consider¬
able testing of the procedure for estimation of sugar was done
and the results of such testing appear in Tables D and E.
TABLE D
Copper-reducing power of glucose and fructose in
terms of .01 normal sodium thiosulphate
Sugar
(mg.)
Glucose
(boiling time -
15 min.)
Fructose in presence of
.221$ KJ
(boiling time - 10 min.)
van der Plank <
Observed
van der Plank
Observed
.125
.52
mmmm
..25
1.06
1.21
.81
.80
.50
2.20
2.30
1.89
1.90
.75
—
3.35
<3X0 <m»
3.00
1.00
4.55
4.60
4.08
4.10
1.25
mm me
5.75
5.25
1.50
6.88
6.90
6.41
6.35
1.75
...
8.10
...
7.50
2.00
—-
9.25*
—
8.60
2.25
10.40*
mmm*
-•
2.50
—
11.60*
2.75
12.75*
—-
—
3.00
13.90*
— —
* Double volumes of all reagents used.
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- 19
TABLE E
Recovery of glucose and fructose added to
plant extracts (results expressed as <?<>)
Recovery
Extract + sugar Extract Observed Theoretical
Glucose
1
1.50
1.14
.36
.40
2
4.18
2.40
1.78
1.88
3
3.87
2.98
.89
.80
4
1.82
.85
.97
.98
Fructose
1
.76
.36
.40
.40
•2
1.58
1.20
.38
.40
Fermentations using the methods described by Yemm
(21) were found to be entirely satisfactory and, while cor¬
rections for the magnitude of the reducing power due to
non-fermentable substances were not made on all extracts,
enough were actually carried out to make this correction pos¬
sible* Results of fermentation analysis are shown in Table F.
~ 01 -
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20 -
TABLE F
Estimates of non-fermentable substances
in plant extracts
Plant age
(days)
On green materials
[io green weight)
On dried materials
($ dry weight)
Charcoal
cleared
Uncleared
Charcoal
cleared
Uncleared
20
.02
.04
.13
.15
30
o01
.04
-
-
40
.06
.04
.03
.20
50
.05
.06
.01
.24
60
o
-
.01
.42
70
-
mm
-
—
80
—
.02
.24
Methods for clarification of non-hydrolyzed extracts
involved the use of charcoal in the manner suggested by
Archbold (1)* Results obtained appear to be in agreement
with those obtained by Archbold. A few of the observed
results are included in Table G.
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21 -
TABLE G
Estimates of glucose in water extracts of
barley before and after clarifi¬
cation with charcoal
Glucose corrected
for non-fermentable
Before fermentation After fermentation substances
Sample
Uncleared Cleared
Uncleared
Cleared
Uncleared
Cleared
1
1*33
1.21
.14
.04
1.19
1.17
2
1.07
1.02
.16
.09
.91
.93
3
1.48
1.35
.23
♦ 07
1.25
1.28
4
1.01
.89
.19
.03
.82
.86
Amounts
of charcoal
used were from .4
to .6 g*
per 100 ml.
of
solution containing
4 g. Of
fresh material per
100 ml.
It should be observed that clarification results in lowered
reducing power, owing to non-fermentable substances but, at
the same time, results in many instances of increase in value
for corrected reducing sugars* It has been suggested by
Archbold (2) that reducing substances other than sugars
diminish the reducing power of sugars present*
The methods which were used in routine estimations
of sugars and which have been referred to, appear to be
entirely trustworthy if all the conditions are carefully fol¬
lowed* It has been observed, however, that the following
precautions should be emphasized:
1* All reagent solutions used must be accurately
and carefully measured.
2* The heating period of 15 minutes must be ad¬
hered to under conditions that remain constant from run to run.
3. The "holding period" at 1°C. for two hours in
0
to
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one of the steps of hypoiodate oxidation of glucose is
exceedingly difficult to maintain unless there is available a
dependable refrigerator. This troublesome factor was success¬
fully overcome by placing the flasks in ice and water mixtures
before placing in the refrigerator.
4. The capacity of the "sugar reagent" to measure
reducing power is limited. It was observed that, if the con¬
centration of the sugar in the aliquot was such that reduction
nearly equalled the blank, results were invariably unreliable.
A difference of at least 1.5 ce. of .01 normal sodium thio¬
sulphate should obtain between reduced reagent and the blank.
5. Addition of charcoal to extracts must be care¬
fully carried out. Excesses of charcoal were found to remove
sugars in rather significant amounts. The amount used should
just clear the extracts and no more. The amounts used, there¬
fore, varied with the amount of pigment present in the solu¬
tions and less was used with older plants than with younger
ones.
6. Neutralization of acidified extracts is very
unsatisfactory if end point of neutralization must be made by
relying on indicator dyes. The difficulty of observing
indicator color change in opaque solutions is great. Some
buffer effect was also observed in the hydrolized extracts.
The use of a portable glass electrode potentiometer is essen¬
tial for consistent results.
c O
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Technique used in the Estimation of Sugars
1. Free reducing sugars were estimated on clarified
extracts, using the modified Harding and Downs microcopper
reagent. Total sugars were estimated after hydrolysis with
N/5 H 2 SO 4 , no clarification being necessary.
2. Separate estimations of fructose were made on clari¬
fied, non-hydrolyzed and non-clarified hydrolyzed extracts.
5. After corrections in free reducing and total sugars
for non-fermentable substances had been made:
(a) Free reducing sugar minus free fructose s free
glucose.
(b) Total reducing sugar minus total fructose s total
glucose.
4. The approximate estimate of fructosan was made from
the excess of fructose over glucose produced by N/5 acid, plus
a correction of 6 $ glucose occurring in the known fructosan.
5. Estimates of sucrose as the difference between
increase on hydrolysis and the fructosan estimate were subject
to large errors and therefore not reliable (4).
6 . A second means of estimating sucrose is suggested
whereby twice the increase in glucose produced on hydrolysis
equals sucrose. These values will always be too high owing to
the inclusion of glucose from sources other than sucrose. At
■ id id d . b rp ta t
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on s
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24 -
best they can only be regarded as approximations (4).
EXPERIMENTAL RESULTS
As a matter of convenience the experimental results
obtained in this investigation are divided into four sections:
Section A - The drifts in sugar and dry matter con¬
tent in growing barley from the eighth day after seeding
to the end of the growing season.
Section B - The differences in sugar and dry matter
content in growing barley as related to the time of day
collections were made.
Section C - The sugar and dry matter content in the
stems, sheaths, leaves, and heads of growing barley from
the 57th to the 85th day after sowing.
Section D - The losses of sugars from barley plants
air-dried at room temperatures.
Seasonal Drift in Sugar and Dry Matter Content
Section A
The results for this section appear in Tables I, II,
and III; and Figures 1 to 5.
The plentiful supply of moisture during the season
'. i ib cold's &1&$ ni jxiIbcMo
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25
resulted in very vigorous growth and before heading many of
the plants had already lodged* The leaves and stems were
larger than those normally produced and long before heading
many of the lower leaves showed yellowing, largely the result
of excessive shading owing to lodging* On only four of the
28 collection days was there no rain in the 24 hours preceding,
and on many occasions it was raining when samples were taken*
The actual moisture content of the material was difficult to
obtain* In this section an attempt is made to overcome this
difficulty, in part at least, by reporting the results as
the average of the afternoon and morning values and omitting
the percentages based on green weight in all except a few
instances*
Heading was practically complete on the 57th day
after sowing* From the 29th day to the 57th day 55 inches of
the 48 inches of the season’s growth took place* Up until
heading the drifts in the concentrations of all sugars were
subject to considerable variation* Whereas there was a slow
increase in total sugar, the free reducing sugars showed a
gradual increase, reaching their maximum content for the
season on the 57th day* Despite the great increase in height
of plants there was no great increase in the percent dry
matter. Many large tillers were produced*
The amounts of free glucose exceeded free fructose
throughout the growth season.
Concentration increases in one sugar usually were
■ ' c
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26
associated with increases in another, so that there was evi¬
dent a gradual upward trend in all of them. This was very
noticeable shortly before heading when increases in all sugars
were large. Throughout most of the period total fructose
exceeded total glucose, the maximum concentrations reached
coinciding with those for the free reducing sugars.
The fructose produced by acid hydrolysis, after cor¬
rections for the amounts arising from sucrose, appears as
fructosan. Except for the rather low values of this sugar
obtained on the 36th and 43rd day there was a gradual upward
trend until the 57th day, when the maximum concentration was
reached. The low values were difficult to explain. The
period was marked by large variations in hours of sunshine,
temperatures, and amounts of rainfall. It rained almost con¬
tinuously during July 29, 30, and 31, and there was less than
one hour of sunshine recorded. The maximum temperature
readings were almost 10°F. less than the July average. The
period following was bright and warm.
The fructosans, at their maximum concentration,
formed approximately 35$ of the total sugar, but the absolute
amounts were not large.
Sucrose was the dominant sugar throughout the whole
period, reaching its maximum concentration a week or so after
the fructosan maximum.
No starch was observed in any of the tissues of the
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27
plants until head formation, when positive iodine tests were
obtained in the head materials.
In the week following heading, the maximum concen¬
trations of all sugars had been reached and, from this date to
the end of the season, a sharp decrease in the amounts of all
sugars was clearly evident. The presence of fructosans in
the plants after the 78th day was doubtful. The drifts in
the concentrations of all sugars almost paralleled one another,
until at the end of the growth period only small amounts of
sugar remained.
For comparative purposes the following observations
may be related to periods of growth.
A. From Sowing to Heading
1. The total sugar increased slowly in the early
part of the growth cycle. At the same time there was a
more rapid increase in dry matter content.
2. There was a gradual increase in the amounts of
both free and combined fructose and in glucose.
3. The sucrose level remained fairly constant.
4. All sugars, with the exception of the total
sugar and sucrose, reached their maximum concentration
at time of heading.
5. This period marked the time of most active
growth and, by heading, most structural parts of the
plants were formed.
6 . Some of the lower leaves were dead by the time
heading was complete
«
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- 28 -
B» First week after Heading
1. The maximum concentration of all sugars was
reached.
2. Head formation began and was accompanied by a
rapid increase in dry matter content.
C. One week after Heading to End of Season
1. The leaves died and ceased to function as centres
for assimilation.
2. The dry matter content increased rapidly.
3. The concentrations of all sugars decreased
rapidly.
4. Most of the starch in the grain was formed
during this period.
On the basis of recent conclusions reached by
workers on this problem, the variable trends of all sugars
in the early stages of growth are due to the great demands of
the actively growing plant for primary assimilates, thus
leaving little for purposes of storage. The leaf surfaces
which are the most important sources for photosynthate in the
early stages were not large enough to do more than supply
immediate demands of growth. It is only when the plants
become fully developed that demands are satisfied and an
excess is produced for condensation to sucrose and fructosan.
This condition should normally exist when growth of the stem
6 a
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58 0X8
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- 29 -
is nearly complete. This is borne out in the observed con¬
centrations of stored sugars found at or near heading. If
the view that stored sugar represents a simple balance of
demand over supply is accepted, then active and vigorous
growth should result in relatively lower concentrations of
stored sugars. The results of the present experiments appear
to be in agreement with these conclusions, since they do not
give the high values observed in plants growing under condi¬
tions known to favor sugar storage.
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30
TABLE I
Field notes
Date of
collection
Stage of growth
Dry
matter
M)
Weather at collection time
June
30
1 leaf
10.9
Cloudy - trace rain
July
1
1 leaf
10.5
Cloudy - rain overnight
July
7
2 leaves
11.1
Cloudy - trace rain
8
2 leaves
10.7
Cloudy - raining
14
3 to 5 leaves
10.2
Fair - warm
15
3 to 5 leaves
11.0
Shower - warm
21
Flag leaf
14.9
Bright - no rain
22
Flag leaf
13.8
Bright - no rain
28
(Some lodging -
17.8
Showery - trace rain
29
( awns showing
14.0
Cloudy - rain overnight
Aug.
4
Head emergence
18.4
Bright - no rain
5
Head emergence
15.3
Bright - rain overnight
11
(Almost headed
21.6
Very cloudy - shower
12
(Almost headed
( badly lodged
19.8
Bright - rain overnight
18
Lower leaves)
25.6
Cloudy - cool - damp
19
yellowing )
23.1
Heavily overcast - no rain
25
(Dough stage;end
28.8
Cloudy - shower in p.m.
26
( of max. growth
26.7
Cloudy - heavy dew
Sept.
1
Many lower )
30.3
Heavy clouds - no rain
2
leaves dead)
28.2
Cool - heavy dew
8
(All lower
34.4
Cloudy - cool; trace rain
9
( leaves dead
35.1
Cool - bright
15
Heads ripening
46.3
Cloudy - cold - damp
16
Heads ripening
43.1
Raining - cold
22
(Plants nearly
47.4
Cloudy - cool - no rain
23
( ripe; some
( tillers green
47.0
Cloudy - cool - dew
29
Harvest
52.9
Cold - rain - snow
30
Harvest
52.3
Gold - rain and snow
05
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31
TABLE II
Composition of aerial parts of barley during
growth (sugar concentrations expressed
as percent green weight)
Collection date
Total sugar
Reducing sugar
Fructosan
June 30
1*08
.31
July 7
.85
.36
--
14
1*03
.28
.01
21
1*31
.52
.35
28
1*21
.63
.21
Aug* 4
1.34
.68
.14
11
1.52
.93
.63
18
3.44
1.16
1.20
25
5.22
1*28
1.09
Sept. 1
5*07
1.45
—
8
3.85
1.16
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15
2.05
.55
oa
22
1.65
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—
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1.06
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OS
Composition of the aerial parts of barley during growth
(Sugars expressed as percent dry weight)
32
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33 -
Figure 1
The drifts in sugar and dry matter
content in growing barley
Note: Weather data shown are those which prevailed in
the day preceding collection.
Dry matter as percent of the green weight.
34
Figures 2 and 5
Composition of barley during growth.
Sugar concentrations as averages of after¬
noon and morning collections
SUGARS % OF DRY WT.
35
Figure 4
Composition of barley during growth.
Free glucose and free fructose as
averages of afternoon and
morning collections
SUGARS % OF DRY WT.
36
Figure 5
Sugar eonoentrations in growing barley
as averages of morning and after¬
noon collections
Glucose and fructose as increases
after acid hydrolysis
'
.
- 37
Section B
The investigation discussed in this section was made
in an attempt to estimate the extent of sugar and dry matter
changes following periods of darkness. At present there is
considerable evidence (8) that losses of stored sugars are
not due to the demands of growth but are apparently related
to respiration*.
Some striking results were obtained in the prelimi¬
nary work when sugar concentrations were estimated in plants
growing under dull and wet conditions. Collections were made
at approximately 1:30 p.m. on three different dates and the
data presented in Table IT.
TABLE TV
Sugar concentrations expressed as percent
of green weight
Collection
date
Age
(dy.)
Total
sugar
Reducing
sugar
Sucrose
Total
glucose
Total
fructose
June 9
15
1.22
.39
.10
.44
.78
June 12
18
.44
.15
.03
.14
.30
June 16
22
.26
.06
—
.21
.05
* Losses have been attributed to respiration activities
although at present no conclusive evidence has been obtained
as to the actual fate of stored sugars (6).
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- 38 -
The period from June 4th to 9th was exceptionally
warm and the hours of sunshine recorded for each day were
much higher than the average value for the month* In the
following week, 4.17 inches of rain fell and there was no
direct sunshine from June 13 to 16. The very sharp and well
defined decreases in concentrations of all sugars were clearly
related to the prevailing conditions of weather, and it would
appear that the low hours of sunlight and low temperatures
influence sugar concentrations because losses due to respira¬
tion are not replaced by photosynthetic activity.
The remainder of the discussion in this section is
concerned with the barley planted on June 22, the data appear¬
ing in Table J and Figures 6, 7, and 8.
The dry matter content in the morning collection
was, with few exceptions, lower than that of comparable after¬
noon collections. The largest differences were noted when
the plants were young and growing rapidly, but for reasons
already considered, the difficulties involved in making mois¬
ture determinations made actual estimates of dry matter
questionable. A definite relationship between dry matter dif¬
ferences and age was observed to exist. After time of heading,
the morning and afternoon differences in dry matter content
decreased with increase in age.
Differences in sugar concentration were not clearly
evident. There is some reason to suggest that the total
sugar values were higher in the afternoon, but the fact that
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39 -
TABLE V
Sugar content of barley expressed as percent
of dry weight, as related to time of
day collections were made
A = afternoon collection
B = collection following
morning
Age
of
plant
Total
sugar
Sucrose
Fructose
after
hydrolysis*
Free
glucose
Free
fructose
A
B
A
B
A
B
A
B
A
B
8
13.76
6.29
11.56
4.20
4 0 95
1.52
1.65
1.81
1.38
.86
15
7.66
1.80
22
10.78
8.64
7.24
6.56
4.12
3.18
1.67
1.36
1.37
.82
29
11.07
6.96
2.68
4.34
5.84
1.67
2.95
2.54
.94
.58
36
8.09
7.00
3.02
2.00
2.87
1.79
2.70
3.14
1.01
1.07
43
8.48
7.32
4.14
2.10
2.28
2.35
2.39
3.00
1.74
.92
50
7.31
7.37
1.28
—
3.01
2.47
1.58
3.58
2.08
1.77
57
14.10
14.16
5.54
4.52
6.41
7.35
3.32
2.90
1.60
1.65
64
17.78
19.92
9.32
12.30
8.57
9.13
2.88
3.10
1.67
1.54
71
20.26
14.15
19.66
12.42
4.95
3.54
3.17
2.34
2.31
2.06
78
11.80
10.34
6.88
8.32
4.91
3.05
1.86
1.59
1.69
1.54
85
4.58
4.59
4.96
4.12
1.07
1.13
.55
.89
.49
.52
92
3.04
3.94
1.68
—
—
.17
--
—
—
99
2.31
1.70
1.76
1.52
——
——
.13
.02
•*—
——
* Total increase in fructose after acid hydrolysis.
some of the afternoon values were lower than those for the
morning makes acceptance of this open to question. The only
real differences were found in the period of one and one-half
months immediately after seeding. Near harvest the differences
were much smaller and were not consistent.
The free glucose estimations varied so greatly that,
with the exception of the first few observations, no consistent
differences were noted. The free fructose concentrations, on
1 ■ -
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40
the other hand, showed real differences and, with only one or
two exceptions, the afternoon values exceeded those for the
morning. The differences in the early stages of growth were
much greater than those noted in the periods approaching
maturity. Increases in fructose after acid hydrolysis were
higher in plants collected in the afternoon, and followed
drifts much like those for free fructose. The differences
again appeared to he significant. The fruetosan values are
directly related to fructose increases following hydrolysis
so that they too follow much the same concentration changes in
relation to the time of day at which collections were made.
The sucrose estimates are at best only approximate
and are always too high, since glucose from sources at present
undefined is included (4). The data on sucrose showed no real
differences, although amounts vary within wide limits.
Great, variation in weather conditions occurred
throughout the growth period. From evidence obtained on the
effect of hours of sunshine and temperature on level of sugar
concentrations in plant material investigated in the early
part of this work, it would appear that rather large variations
must accompany weather changes. If, for example, cloudy con*
ditions prevailed previous to the 4:30 p.m. collection and
clear bright weather followed until nightfall, no normal esti¬
mate for that day could be expected. The observation for the
morning collection on the other hand would be dependent upon
the conditions which obtained from dawn to 8:30 a.m. If
/ ■ , ■
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SIlL 1 X j ,:.jJ v 0 -j IB I i J O J. J. dj 4
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41
storage and formation of sugars is greatly influenced by the
hours of sunshine during the period before nightfall and the
period preceding 8:30 a.m., the effect of darkness becomes
obscured. This difficulty could be overcome in future work
by taking the "afternoon" collections at sundown and the morn¬
ing ones somewhat earlier than 8:30 a.m. As the data appear in
this report, little can be known of the effect of the hours of
darkness, since some hours of daylight occurred in the inter¬
val between afternoon and morning collections. The differences
between morning and afternoon collections, nevertheless, did
indicate a large daily variation in sugar content.
Zt
ei\;c .•.■1“;::.. : .
J . .. ' I.jV.J' i-
'
s -r.o'ii o •- - iio 3x11 tjj r on r va ±0 siron.
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.
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nwoi • .. 11 . t ■ J
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► I ■ ' . ' . wcfod 1m
: .
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42 -
Figure 6
Dry matter and total sugar content in
growing barley as related to time
of day collections were made
43 -
K-
Figure 7
Free glucose and free fructose content of
growing barley as related to time of
day collections were made
44
Figure 8
Sucrose and total fructose in growing
barley as related to time of day
collections were made
45 -
Section C
This portion of the investigation fell considerably
short of original expectations. The analysis of the separate
parts of the whole plant was undertaken so that an estimation
of the level and the time of occurrence of maximum concentra¬
tions of sugars could be made* The results obtained indicate
that the maxima had either been reached or nearly so in all
parts at the time the first analysis was made and, as a con¬
sequence, only the "falling phase" of sugar trends was ob¬
served. The data are presented in Tables 71 and VII*
In all parts of the plant there was in increase in
the dry matter content, the larger increases occurring in the
stems, leaves, and heads. As the first observations were made
at approximately the time of full heading, a good picture of
the dry matter increase in the head was obtained. Dry matter
changes in sheaths were small. Some doubt may be cast on the
results obtained for the leaves, as many of the lower ones,
especially in the later periods of growth, had either dropped
in the field or were lost in handling. At best the results
should be considered only as approximate estimates.
The large increases in the dry matter content of
whole plants is closely related to increases of dry matter in
the heads. By the time heading was complete it may be assumed
that most of the structural parts of the plant had been formed
so that changes of dry matter in all parts but the heads were
caused by loss of water and tissue degradation, associated with
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46
TABLE VI
Sugar content of steins, sheaths, leaves,
and heads of barley, expressed
as percent of dry weight of plant
Date of
collection
age
Stems
Sheaths
Leaves
Heads
Total
Whole
plant*
Dry matter
as % of
fresh weight of whole plant
Aug. 18
57
<■»«»
•mwm*
25
64
39.3
13.6
18.8
38.4
28.8
Sept. 1
71
37.9
13.1
16.1
33.4
30.3
8
78
35.5
13.6
13.2
37.7
34.4
15
85
35.3
13.6
7.2
45.0
46.3
Total
sugar as % dry weight of plant
Aug. 25
64
9.01
1.86
2.30
4.93
18.10
17.78
Sept. 1
71
8.61
1.80
1.96
4.51
16.88
20.26**
8
78
5.21
2.01
1.55
2.08
10.85
11.80
15
85
1.74
.64
.21
1.31
3.90
4.58
Free glucose
as % dry weight of plant
Aug. 25
64
1.86
.40
.47
.33
3.06
2.88
Sept. 1
71
2.04
.40
.48
.54
3.46
3.17
8
78
1.32
.52
.38
.13
2.35
1.86
15
85
.29
.13
.06
.10
.58
.55
Free fructose
as % dry weight of plant
Aug. 25
64
.86
.18
.23
.22
1.49
1.67
Sept. 1
71
1.53
.38
.32
.21
2.34
2.31
8
78
1.22
.39
.27
.10
1.98
1.69
15
85
* 51
.15
.04
.09
.79
.49
Glucose
} as net
increase after hydrolysis
as
% dry weight of
plant
Aug. 25
64
2.17
.55
.65
1.45
4.82
4.66
Sept. 1
71
2.45
.52
.57
1.49
5.03
9.83
8
78
.75
.37
.77
.47
2.36
5.30
15
85
.37
.06
.07
.90
1.40
3.03
p t,
t
.. . ■
0 £. 08 ;.
v>."■ * K * .. I V
< .. --n ^ ' ‘ r
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;le
L
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‘j:os rJ'w't a3 oeo^/Jl
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6 V
CJ.
47 -
TABLE VI (continued)
Date of Whole
collection Age Stems Sheaths Leaves Heads Total plant *
Fructose as net increase after hydrolysis
as % dry weight of plant
Aug.
25
64
4.11
.73
.96
2.94
8.74
8.57
Sept,
, 1
71
2.59 .
.55
.58
2.27
5.99
4.95
8
78
1.92
.75
.13
1.38
4.18
4.91
15
85
.21
.25
.04
.24
.74
1.07
Fructosan as % dry weight of plant
Aug.
25
64
2.21
.20
.35
1.70
4.46
4.45
Sept.
1
71
.16
.04
,01
.89
1.10
—
8
78
1.33
.44
—
1.04
2.81
1.79
15
85
.21
.21
—
.42
—
Sucrose as
% dry weight of plant
Aug.
25
64
4.34
1.10
1.30
2.90
9.64
9.32
Sept,
1
71
4.90
1.03
1.14
2.98
10.05
19.66**
8
78
1.51
.71
1.53
.94
4.69
6.68
15
85
.74
.12
.13
1.79
2.78
4.96
Reducing sugar as % dry weight of plant
Aug.
25
64
2.72
.58
.70
.55
4.55
4 0 55
Sept
. 1
71
3.57
.67
.81
.75
5.80
5.48
8
78
2.54
.91
.65
.23
4.33
3.55
15
85
.81
.33
.10
.18
1.42
1.04
* Obtained on the whole plants on the corresponding dates of
collection.
**The apparent over-estimation of the increase in glucose
after hydrolysis gives:
1. Too high value for sucrose.
2. Low value for fructosan.
3. Too high value for total sugar.
crnoo
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48
TABLE VII
Sugar and dry matter content in the stems,
sheaths, leaves, and heads of barley
Date of Age of
collection
plant
Stems
Sheaths
Leaves
Heads
Dry matter of the part as % of green
weight of
part
Aug. 18
57
32.1
24.2
19.2
30.8
35
64
30.0
26.6
24.8
39.6
Sept. 1
71
25.7
24.6
22.9
39.8
8
78
27.4
26.4
28.2
49.0
15
85
32.6
29.6
55.0
53.8
Total sugar as % of dry matter of part
Aug.
18
57
31.04
17.11
9.74
12.08
25
64
22.93
13.68
12.26
17.37
Sept
. 1
71
22.72
13.25
12.18
13.92
8
78
14.67
14.81
11.77
5.51
15
85
4.94
5.04
2.87
2.92
Free glucose as % of dry matter of part
Aug. 18
57
10.22
3.06
2.60
3.02
25
64
4.73
2.94
2.50
1.16
Sept. 1
71
5.37
2.97
3.01
1.66
8
78
3.72
3.86
2.90
.34
15
.85
.83
1.07
.80
.22
Free fructose
as io of
dry matter
of part
Aug. 18
57
2.04
2.27
2.34
25
64
2.20
1.35
1.21
.76
Sept. 1
71
4.05
2.15
2.01
.65
8
78
3.43
2.84
2.06
.27
15
85
1.46
1.22
.58
.19
Glucose as net
increase after hydrolysis
as °/o of dry matter of part
Aug. 18
57
3.13
5.58
2.11
25
64
5.53
4.05
3.47
5.10
Sent. 1
71
6.46
3.94
3.54
4.60
8
78
2.12
2.62
5.82
1.25
15
85
1.06
.49
.91
1.99
>t .8 6
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49
TABLE VII (continued)
Date of Age of
collection plant_Stems Sheaths Leaves Heads
Fructose as net increase after hydrolysis
as jo dry matter of part
Aug. 18
57
15.65
6.20
wa> mo
4.61
25
64
10.47
5.34
5.08
10.35
Sept. 1
71
6.84
4.19
3.62
7.01
8
78
5.40
5.49
.99
3.65
15
85
1.59
1.96
.59
.54
Fructosan as °/o dry matter of part
Aug. 18
57
14.27
.71
2.85
25
64
5.63
1.47
1.84
5.99
Sept. 1
71
.43
.29
.09
2.75
8
78
3.74
3.27
--
2.74
15
85
.61
1.68
--
—
Sucrose
as io dry matter of part
Aug. 18
57
6.16
11.16
OWQMI
4.22
25
64
11.06
8.10
6.94
10.20
Sept. 1
71
12.92
7.88
7.08
9.20
8
78
4.24
5.24
11.64
2.50
15
85
2.12
.98
1.82
3.98
Reducing sugar as % dry weight of plant
Aug.
18
57
12.26
5.33
2.60
5.36
25
64
6.93
4.29
3.71
1.92
Sept,
. 1
71
9.42
5.12
5.02
2.31
8
78
7.15
6.70
4.96
.61
15
85
2.29
2.59
1.38
.39
1 ro a? ro Q>
{ Hv; jjnl ctaoo ) IIV
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50
senescence.
The most significant results were obtained for the
dry matter content of the parts as related to that of whole
plants. The distribution of the dry matter of whole plants is
briefly summarized in Table VIII.
TABLE VIII
Dry matter in the parts as percent of
dry weight of the whole
Part
57th day after seeding
85th day after seeding
Stems
39.3
35.2
Sheaths
13.6
12.6
Leaves
18.8
7.2
Heads
28.4
45.0
The changes in dry matter in stems, sheaths, and
leaves were associated, for the most part, with tissue degra¬
dation which occurred during the period of ripening. The
increase in the dry matter in the head, on the other hand,
was directly related to the accumulation of starch and other
materials in the developing grain. At the beginning of the
study stems formed the larger portion of total dry matter in
the plant, while near the end heads formed 45$ of the whole.
In all parts, except heads, two factors responsible for dry
matter changes were: first, the loss of sugars from the
tissues; and second, the changes which are related to dehydra¬
tion and the transformation that living tissues undergo in
* t
■ ’ : : i
■ ' i ' '
' . _ ^ * 8
. ■' 'o.'I' :cf
IIIV KiaAI
le *'£$*[ SB al-XBq eill x,i ’xad\t-v; 'ixC
Iq J*r£;
■ •.••• / 'V v,": ivCi^ ,,i
■ '
S. ■a
ama tfS
I
a, ri
aAA bo ns
■
e. a i
.
o.ei-
a,; .
Sl)J 89 H
t j
' i'i ItltJ ■ . s
t . . ' ■ •
01B ■ ' .
♦ ni i
n.c ir ;]\t IbAoJ 1o aoltf'ioti xa^aX • or A dqzvio'x sscatfa vlxid’S
• ■ . ' . ■ \ .
:
.
. ' I ;
51
the ripening period. Archbold (5) (7) has found no evidence
of breakdown of any tissue during growth for purposes of sup¬
plying the developing grain with starch-building materials,
so the changes that do occur are associated only with senescence.
It is clearly evident that the change in dry
weight is the result of dehydration and death of tissues, at
least insofar as the stems, sheaths, and leaves are concerned.
More information would have been obtained had the analysis
been carried out on a "per plant" basis. The results would
have shown the actual quantitative changes in dry matter and
sugar content instead of the percentage changes, which indi¬
cate relative rather than absolute quantities in each part.
The estimations of the various sugars were made for
each part of the plant and for the whole plant. When a con¬
sideration is made of the possible sources of error in sampling,
and of the errors which result from carrying out so many
separate steps in the actual analysis, it is concluded that
reasonably good agreement was obtained in all but a few cases.
The results for the whole plants collected on September 1st
appear questionable.
Most of the sugar was found in the stems and the
heads, and this was especially true in the earlier stages of
growth. The concentrations of sugars in the stems and heads
had reached their maximum levels at or near the time heading
was observed to be complete. As nearly as can be determined
the maximum sugar levels for sheaths and leaves had been
58X* to ; O
. -
. ’ - ■ ' '
agiUBfio
s £ al d
■
'. . . >Ix/o\ . ■ i ■ ' i ©s
)
■ C ■ : . . .
I . , . it - • ' » Bi ■ ' . IBgJ
loa< . • ■. ' l
, .. v:e. . , . . U i I C1 i i :
. '
. . . . . / . ' ' 2j
Vi oa v-.-o \:.c %'l $Ls;ue*i t oh/vi c r j to .gjeb
. ast ' ■
:t .. a
* ol ; : : .• ■'.- : , _b
£ji j au.da aiicf ni. bxiuo'i anw ‘ib^jjb exfcfr 'to tfsol*
... . • ' t 8JbB8J
• ■
oi:J ij.-jn lo -t. •. a leva I flu/mlxmx nierUJ’ benoBov bad
.
at vr-..; : bn s.ldxorfa •xol sloval is:,--, jus erio"
aesu bad
52 -
reached earlier.
Throughout the period the total sugars in the stems
was about twice that found in the heads, and approximately
four times the observed values for leaves and sheaths. The
order of the contribution of sugar each part made to the plant
was therefore:
Stems, approximately 50%
Heads, approximately 25%
Sheaths and leaves, approximately 25%.
Individual results varied somewhat but the above is
a fair approximation.
In the 28-day period there was a marked decline in
concentration of the total sugars in both stems and heads, and
this decline was closely related to the changes in total
sugars estimated for the whole plants. The trends in leaves
and sheaths were not so obvious except near the end of the
period.
The greater part of the free glucose observed in the
plant is contributed by the stems. The amounts found in the
other parts were much lower and, on the whole, there was little
difference between the concentrations found in various parts.
The same relationship exists for free fructose, except that
all parts contain somewhat lesser amounts. The lowest con¬
centrations were found in the heads.
The values for glucose and fructose, as increases
after hydrolysis, show definite trends, falling steadily from
the 57th to the 85th day after seeding. The higher concentre-
- X ~
. ' , ' :lr;rr. V.
qsL$ iC: snagi/s iBXoct Ddd u c 1'ieq. siXi fuod^m&I! '
•\ : '. ,X '.B.' a ."..•£(B t «iV* 3 li B.X,/ ' /':•]■ BOX J.:.\t OOiv/X Xirod.8 SBW
: . ;, ..... . .. ::.... '. .a - ■.'■■■■■ - ; .t a; .■ a, a. "...:
; * ' . 1
- lie x.-. •■•...• ... • £ ./::*> . a uadtX
£v-X vXdaax: d-:-,x:,' ( a r 'a;xH
ci x " - ;:'V. ..a;: r J ..
. : tvIJbn'
*a;., .dXov:a, /us aXa/; B
....' .. . ..XX c X 5a -•••.: ■: xa'X £ ..£. a •' ^XD-od a I
'
. .
l.a:X £ : / . q aXa -wd daa.xX-Bi %lei>61s av-x iai.uX&D allIX
. I
■
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.
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t , ■ * i ' ■ '
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;,a,; - ax X ax . oac* / hb occojj.lx 'ioX aorlxv ex£’
. . •
- ' . >ee a : ■
53 -
tions were again observed to occur in the stems and heads,
but there were some (differences in the amounts found in the
leaves and sheaths.
When reference is made to the sucrose levels in the
sheaths and leaves it is apparent that a larger increase in
glucose observed in the leaf material would be expected. The
fructose differences in leaf and sheath material are less
obvious, since the larger amounts of fructosans in sheaths
tend to obscure the effect of the increase of fructose from
sucrose.
The fructosan concentrations in all parts of the
plant varied greatly. There was good evidence that the smal¬
lest amounts occurred in the leaves and the greatest in the
stems, especially at the time active growth of the stem
ceased. The heads contained significant amounts, and when the
fructosans in the stem are considered, practically all the
fructosans in the plant were accounted for. It is difficult
to say just what the general trend was from the few values
which were obtained. Generally, the drifts in the whole
plant are related to the drifts in the parts. It appears
that the maximum concentration reached occurred at the time
heading was complete and that, in the period following, the
amounts decreased rapidly.
The sucrose concentrations followed trends similar
to those for other sugars. The only significant fact ob¬
served was that the sucrose formed the highest proportion of
.... e *zsjoz ■ ' i no id
,... .V'-o'C . ,1.3 CCYCvI
■
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81 .. . . .■ V , ■ 3 ©i ■ - . .. • - l 8 . ' 13 ' '
U380d * . IBi . s • oiV
©aoiox/H vo vbbovqiiI evl- t: d osftlx .vt evvoacfo ol In©*
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V ■ » UBSOCh " ■ 91
-V a s •- : . -
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V ' ; ' . V . 89 { «
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Lb x \ - - ib t ■ i$ ai i c v
■jW
;,-jy .•/©*> exit .cove a by. Velvet ■ VC exit loilv; v3.lv; vcc oV
o ni .
[1 '
. • ! ' XnolXB ■ • t
* ■ V / •. . : c , •; vv j ce n
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„ ■
r : .i ii. j o x !. -v- ’C; ta9iiv-‘:il oilu lev/iol' c aonoua
V .C’C SBV7 Vo vies
54 -
the total sugar in almost all parts of the plant and through¬
out the period could be considered the dominant sugar.
Of all the sugars considered, the free reducing
sugars were subject to the least variation. This fact was
noted in other parts of this investigation.
While the period considered is rather short, never¬
theless a few general conclusions can be drawn. Up to the
time of heading and for a short time after, stem constitutes
the larger portion of the dry matter of the whole plant. In
the later stages of growth, especially during the ripening
period, the heads contain almost half the total dry matter.
In the period following heading, the stems and
heads contain almost 75$ of the total sugars found in the
plants and generally show the most marked changes in both dry
matter and sugar content. When the various sugars in the
plant are at their maximum the stems contain the highest pro¬
portion—as much as 50$ of the sugars.
The sheaths and leaves contained less sugar than did
the ears , and the variation in concentration as related to
the age of the plant did not follow drifts which were as
obvious. At no time was there much more than 25$ of the total
sugar ascribable to leaves and sheaths. This, of course,
would not be true in the early periods of the growth cycle.
Any changes in sugar concentrations which occurred in either
of these parts took place in the latter part of the period
under consideration.
- .../o' ■' ■ ..u ‘io; i Co i oooC.., ‘ • • .m 3
: ' ' '
1 ••■■'1 • 'U 0 .,.‘1 1 lljjl- O/lj .LU* 'IU
. < i ■ .
. uoi -j , i . " i ' til v .. Bvii:. i - ■ a 2 Ik ;j ;n
al
j i onoo
, ■ 1©
TEeg^CB u
.
* .. , xnoo a & <f»oi
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j .• t . ; • , ■ '. J' : {
-; •: .• • • :2 -Gt-toko .k;. ; .\r.;o o io-, out =. c-...i C; giggio ; k:;:.3 Bkiojk
■ . ns » . . ' . ' ■ s ; . ■i ;
- ! ... . ,
* ..... ■ .... .k: v / .., .... ' '1...0. ': o o.;o .
/ok a J' 38G.C huh.! sente o as'vosl kts b CtoJi sxiT
a$ Jbekkoa
SB
ac Cd'i^xina onoo
.' . t 1 : 3 ■ : ■.
01. 3
' .5.03 ,
.
sb slew
■. .. .... ..; ■. . wc:
. ■'.. .'....
•<•; f ■
" .exit
tO 8 8 . fit
Gv ©die}' lo v
gS
lake!' ot-.ciu iior;
•1 o'J-Sl. \) l.tJsSvi Os
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on dot
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. ...' *3 .a ■ '■'■■■••
n i k : ..... fi
. .. '
. . . . ■ . .' . ' . '
*.dkoteikosi o F :ebL ;
55
All parts of the plant at the end of the Q5th day-
contained relatively small amounts of sugar. Sucrose was
the dominant sugar and free fructose was observed to be pre¬
sent in the smallest amounts.
As nearly as can be determined the maximum concen¬
tration of sugars was reached in the following time order:
leaves, sheaths, stems, and heads. This is, of course, just
what would be expected. Concentration trends of all sugars
in all parts of the plant were related to the sugar concentra¬
tions in the whole plant and appeared to be influenced very
markedly by the stage of development of the plant, this being
especially true during the latter stages of the plant’s growth.
Section D
The data for this section are presented in Figures
9 and 10. All sugar values are expressed as percent of the
weight of the material observed after drying for S4 hours in
an oven maintained at 55 to 60°C., this low temperature being
necessary to avoid fructosan destruction.
A comparison of the seasonal concentration drifts
of the total sugar estimated in both green and dried material
indicated close agreement. The total sugar values in dried
materials were much lower but closely paralleled correspond¬
ing values for total sugar in the green materials. The
maximum total sugar content after drying of the plants was
*;a is to bos o i/cr .1.a/oi, e>Ivt to vt'ZBq 11A
# . 5 J
. ' ; i r ,: ■ . sell - . . : ■ I -
, s ;• .X. J is ■.
t ±m . 0
;
t . * * t *
> j .
2li&
vs.7 I>;:i o It Hi Si Go teXSdqrjO OOH Ui;;-...G 8lOtO Or J' ;t.I MOl-t
' •' ■ 1 tO rj . , .
. »
D. . .LitOOt
:SCO. '■
» ' .1 ■
r..; ool o.V;0. ‘xecile lotto too £b : vs : -si en: to Lsv
t *C°Od
, •■•..: ; oi ..i o .•£.■ .£.:s • ■ ■ i • . / i ' .1. ■ 1 •: •' es.
■
i
1 siit/ss '.../so d$QiS ttl b9 : ls;;;oa IfiifrOtf eri.T to.
*
. t ' s;' . tJL/Cf BlBj
.
, so i• iiq .o;'s to toil--: iSvit jxxctooo issctotf hi/o/lx^x
56 -
11.95$, which was almost 37$ lower than the maximum concentra¬
tion before drying. Larger losses occurred with young plants
which had been growing rapidly. With increasing age of the
plants losses were not as pronounced. No "average" losses
could be estimated but an approximation of from 25 to 45$
would include most of the individual values determined.
Concentrations of reducing sugars after drying
showed that losses varied with age of plant, the greater dif¬
ferences occurring when young plants were dried. In these,
there was a marked reduction in free glucose resulting in the
presence of larger amounts of free fructose than of free glu¬
cose. In the older material the losses of both of these
sugars appeared to be less evident, so that amounts remaining
were as high as 80$ of the original values.
Very large losses of sucrose were noted and, since
this sugar made up the greater portion of the total sugar in
the plants before drying, its disappearance during the drying
period accounted for most of the sugar lost.
Fructosan losses did not appear to be large, the
only obvious differences occurring in the younger plants.
The losses in reducing sugars that actually occurred
during drying are difficult to determine as sucrose inversion,
which is broight about by enzymatic activity during drying of
the plant, would increase the concentration of both glucose
and fructose (1). The demands of respiration before death of the
,£ •' ' ’ c • “ *
-
■ •. ' .. ■ 1 * ' o ■■■. ^ ' •' •
‘.'-.O \0 V 0 O V;- ,W ; t .„;0 C)d ■ S.: GO
.. i ivihnl
' ■. • ,. fti > lo ii' ©no?
- .1 t i :
■ ■ ■ X : c [
i■ J £ ■ i a : :
~ul . • ' ' : . 80' SdlttK to
ocf lo
>s . - 1 ■
* *B1 : 5
) T
: .: u . U ■■ 1C . ■ ’ i ). UT i : ' B § J 3 .... I ■
'
„ .) ... . ■■ '. ■■, ‘ . ,. ■ : ■ . mV):: 0 : c ■ 1
v &0£X 8 3 X . ... « 0. .
■
.om-vvooo o v\.X v. voo c v'-' uv-x *. f a Go. GOOcoj. c.. v
‘. od sjoI
i u : . ' . c - i 1 ■ 3 .■■■■•. ■ \ < ' i . <
r. . : ;v V ' .• ’v.; .v- o . '.J :v, ,v.v ov r \ O',, t 1 o
. (
57
plants, however, reduce the amounts of the latter sugars so
that the amounts remaining would depend upon the extent of
sucrose inversion and the magnitude of the demands of respira¬
tion. The results indicated lowest concentrations of reducing
sugars to be associated with the smaller amounts of sucrose
originally present. This phenomenon would also account for the
relatively higher concentrations of reducing sugars observed
in plants that contained large amounts of sucrose before dry¬
ing.
It was concluded from the observations on sugar
losses that occurred during drying of plant material that the
most labile sugars were glucose and sucrose, whereas fructose
and fructosans were the least affected. The levels of reduc¬
ing sugars in dry material were related to concentrations of
sucrose originally present. The over-all losses in total
sugar, due to drying of the plants, was from 25 to 45$.
■ - t
io 73© ' o; Mx/cv* oiiiniBnon stiiuoL-j* coct
e-i no • oJj G'o oo; ; cooo: .... : '-no r : ''. ^-oova.: ooooooa
x
v 7 .. . 7773 ; '.: G £30 73 : : $ [. 7.78 6,'Kj' J i . 0,, Coi Of. 77 ' ©C ' • 'J ci7. 8
'
. l ) . . . . j ? 1 •' t i . . . . 1
■ ■ ' . >0 ... 7.
•jft, r -
<r
‘1.677 7 no ano.ro ovoo acfb e/I? ooob iterrlortoo a no I
si g c' jJ. t\*ii ' n • .■ ./ .
. t : . " s i t I ci
. ■
?::> c 'i,.Jo .77777 ,,7 7 07 00J sS.^l 7007 In* ooCfo: '' •7;.,;) oi a037,7c 0,07
L -- . v< . al 1
. . .. • ' o c 7 .0.070 .. : ■ 7 bo . c:!* . o ■> ? 7;
58 -
TABLE IX
Composition of dried barley plants
(Results expressed as fo dry weight)
Free
Age of Total reducing Free Free
plant sugar sugar Sucrose Fructosan glucose fructose
8
4.05
1.22
15
2.55
.93
22
3.44
.83
29
4.10
.93
36
2.39
.48
43
1.94
.52
50
5.55
1.66
57
11.03
3.28
64
11.95
3.80
71
10.05
3.08
78
7.17
2.58
85
5.21
1.64
92
2.17
.94
99
.64
.28
3.92
...
2.76
—
2.68
—
2.08
1.24
1.34
.57
.46
1.09
1.56
2.66
6.12
1.86
4.82
3.80
6.36
.70
4.52
.07
2.98
—
.34
.88
.04
.89
—
.94
.17
.76
—
.55
.11
.41
1.02
.64
1.89
1.39
2.22
1.58
1.84
1.24
1.31
1.27
.87
»77
.64
.30
.15
.13
- .
.el'i.jcf bui'ib '.:o aoi$
si'lb t;; 'J.8 ii9 8Uv J I-p vj
(
' .
9811,
*? 300 If X.-
rt gP 0 r.^f‘V f.
8 $
/ ? 0 if T &> * f
•l rj.^ .
■XscfoT ::o
<w* 0 .«q f rp ; 4 ^ p
r #
:■ v. * 0
■■> # :;
cC ,0
0
. 0
G 6 *
J <’ *
cc, :
1
•n *\ <5
p .• •. <J
o. *
ss
po
■ t. #
*> •
1 j- *■
J3 53
1 • >4
„ —
np ■
* x
8 x 1 "
oS
I £ *
» . :
’ ■ ■ ■ 4
:ir , /.
»
i-3.
•!: d *
0 0 , X
0 •. -
03
r
•* « * •
.
£*
* ■
VS
.i
,
C 8,0
5 .. . * i.
X
00 . .LX
xa
!.
0 V .
*
60, X
0 ).cr.
IV
VS* I
X- ..
O 53 <'*
■VI."
8 V
VV*
• ■ *
•
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IS. c
SB
(. »
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in *
V £,0
S ;0
• - - • • #
ti.
■** ^
9 C
SUGARS % or DRY WT.
- 59 -
Figure 9
Sugar content in dried barley plants
Results as averages of afternoon
and morning collections
60
Figure 10
- Sugar content of dried barley plants
Free glucose, free fructose, and sucrose
results as averages of afternoon
and morning collections
61 -
DISCUSSION AND SUMMARY
Quantitative determinations of sugars in growing barley,
with the object of studying seasonal changes and drifts, were
carried out. Relationships were found among concentrations of
stored sugars, stage of plant development, and growth rate.
Weather conditions seemed to be related to rate and extent of
sugar accumulation.
When growth rates were high no large accumulations of
sugars were observed, although during this particular period
most of the vegetative parts of the plants were formed. Sharp
increases in all sugar concentrations were noted only when
active stem elongation was near completion. Maximum concen¬
trations of all sugars occurred at or near heading. It would
seem that in the early periods of the season demands of
growth processes utilized most of the available assimilate
and that only after full growth was nearly attained was there
a surplus of photosynthate produced for purposes of storage.
Sucrose, always the dominant sugar, rose and fell
with the other sugars and there appeared to be no evidence
that the rise in one was associated with the fall in another.
Any changes in ratios were apparently due to a relatively
faster increase or decrease of one or the other. Concentra¬
tions in all sugars rapidly declined soon after heading until
at harvest only small amounts remained.
- lo
... , CM. ' 1' ■: JOCK ■
. * ' ’ ■ .: J i . ■' . ,
n ■ - >8 . - i ■ , .
• ■- : 1 I * '' ' 1
* . .... ... '
l' . i .. t - ; & . . . : . . : . . os ! s
. ' . .. :-v JJ 8
. ■ icC ... r . :C •>. .j., . ■ sjoi t b« y‘.:e&-2 o sievr eU3£i/a
[Sd . 8J ■ . ■
Ino • . .. : • ■ ■ o ; . ., n 1 . %pixl
• . i t , , i. •
■ ■: .. ■ ■ ■ • id ■ '
. ,
eta': ■
......... £* . ■ . 3 £ l % •
u ,.. ' r. , ' - lui■ 3
I t Q*li
. . :. ■ . - i I ©J
. j h . J ■ o. . . \ ■ i
5
- ■ ono* . . . ■ ■
21; . “la . : '. i $
. • . . 5 .. ■
62
The conclusions reached by Archbold (5), Archbold
and Datta (7), and Archbold and Mukerjee (8) emphasize the
point that sugar storage is the result of a simple balance of
supply over demand. The observations and results of this in¬
vestigation support this view.
The seasonal drifts in the concentrations of all
sugars, as observed in this work, are in general similar to
those reported, but some differences were apparent.
The observed amounts of fructosans were lower, while
the estimations of sucrose were higher, except for Barnell's
(9) (10) values for wheat. The proportion of fructosans to
total sugar at the time the maximum concentrations were noted
was 35$, as compared with reported values as high as 60$ (4).
Free reducing sugar exceeded fructosan concentrations. The
presence of fructosans in leaves was not clearly demonstrated.
The drifts of sugar concentrations in each plant
component were similar to those observed in whole plants, but
had different time relations. As nearly as could be determined
the maximum concentrations of sugars occurred in the following
time order: leaves, sheaths, stems, and heads. During the
period considered, the stems were found to contain approximately
50$ of the sugars found in the plants; heads 25$; and sheaths
and leaves the remainder. The most apparent decreases in
sugars during ripening of the plants occurred in heads and
stems, but near the end of the season large losses from all
parts were evident.
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- 63 -
Losses of sugars from the stems, sheaths, and leaves
were related to senescent changes in these parts. Fructosan
concentrations were greatest in the stems and young heads and
account for most of the fructosan in the plant. Amounts of
fructosans in all parts of the plant were lower than those
recently reported by others (4).
The attempts to obtain quantitative evidence with
respect to overnight losses in sugars were not very successful,
largely because conditions were extremely variable* The few
real differences obtained indicated that free fructose and
possibly fructosans were affected. The values obtained for
the other sugars were so inconsistent that no conclusions were
possible. No reference to diurnal changes in fructosan in
growing plants was found in the literature, but the results
of an investigation on sugar concentration variations in
alfalfa as related to time of day, reported by Curtis (11),
indicated that large overnight losses were possible. On the
average, afternoon cuttings were 83 % higher in carbohydrate
and 19$ higher in dry matter yield than were the morning cut¬
tings.
The dried material contained considerably less sugar
than did the corresponding samples of green material. The
observed loss of between 85 and 45$ was found to fall on the
free glucose and the sucrose fractions. Fructosan losses
were larger in younger than in older plants, although the
all-over decreases noted on drying were less than for sucrose
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64 -
or free glucose. Decreases in reducing sugars were not evident
in plants which originally contained high concentrations of
sucrose. The possibility of sucrose inversion to free reduc¬
ing sugars was suggested.
This preliminary survey of some of the quantitative
variations in fructosan accumulation in barley indicates that,
under normal conditions of growth, there is an increase of
fructosan in the whole plant, at least until stem elongation
is complete. Subsequently the amount falls as the total sugar
declines and the grain ripens. It was evident that the accumu¬
lation of fructosans did not occur until conditions which pro¬
mote sugar storage were present. The ultimate maximum level
of fructosan was associated with the concentrations of the
other sugars, while the increase with time was due to increas¬
ing sugar content. On the basis of these observations and
from the conclusions reached by Archbold et al, it became
clear that fructosans only accumulate under conditions which
promote sugar storage. Furthermore, sufficient evidence has
now been obtained to reveal the fact that the accumulation
and fate of stored sugar, Including fructosans, is not the
result of simple, easily understood physiological processes
or the result of any one environmental factor, but rather a
complex, interrelated combination of all the many factors
which modify and determine the normal growth of plants.
Therefore, for the present and in the absence of
much more detailed and precise information, it can be stated
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65 -
that the possibility of a successful fructose industry using
raw fructosans from barley is slight* The only assurance
that may be offered is that the actual yield of fructosans
from barley grown under normal field conditions will be
extremely variable and difficult to predict.
Attempts to breed a high-fructosan barley would be
premature in the face of present knowledge of the large and
profound effect of the many factors, both environmental and
physiological, on fructosan storage.
Some indication of what remains to be done before
our knowledge of fructosan formation is complete is revealed
in the following quotation taken from Archbold (4): "Only
when it can be stated with certainty under which circumstances
glucose and fructose are interconvertible in plants, and when
some knowledge has been acquired of the mechanisms involved
both in such conversions and in polymerisation, will real
progress in our views on fructosan formation be possible."
In the opinion of the writer, more information and
precise results from this study would be obtained if some of
the following modifications were adopted:
1. Samples for analysis should be based on a known
number of plants and results reported on the quantity of sugar
and dry matter per plant.
2. Since the variation in sugar content with time is
great, analysis should be made more frequently than once a
week.
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66 -
3. Dry matter content and sugar concentrations based
on the percentage of green or fresh weight are difficult to
estimate with any degree of precision if free water adhering
to plants is not rapidly and completely removed. At present
no means of removing such water completely are known, but the
use of blotters has been suggested.
4. The period selected in this investigation for esti¬
mations of "overnight" changes in sugar, water, and dry
matter was very unsatisfactory as varying hours of sunlight
were included. Plants for the estimations of the effect of
daylight should be selected near sun-down. Plants selected
for the "morning” collection should be covered the evening
previous or collected soon after sunrise.
Finally, the following points should be borne in
mind in any future work on the problem of carbohydrate
storage in plants:
1. The techniques for analysis of sugar in plants, now
generally in use, while greatly improved over those formerly
employed, require further refinement. More information as to
sources of the glucose that are at present undefined is
required before a completely satisfactory technique for esti¬
mation of sucrose and fructosan can be devised.
2. The large losses of sugars observed during ripening
or drying of plants require explanation. The suggestion that
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67
these and overnight losses are related to respiration has
been advanced but is by no means conclusive,
3. Recent observations made by Archbold and Datta (7),
Gregory (18), and Richards (16) on carbohydrate storage and
utilization indicate that nitrogen compounds are involved.
The study of the interrelations of these two groups of com¬
pounds appears timely,
ACKNOWLEDGEMENTS
The writer’s thanks and appreciation are extended
to the supervisor of this project, Dr. A. G. McCalla, for
helpful criticism and advice during the progress of the
investigation. A. E. Harper assisted in the routine analysis
and G. M, Tosh in the preparation of equipment and photo¬
graphs.
Financial assistance was supplied by the National
Research Council, Ottawa
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REFERENCES
ARCHBOLD, H.K. Ripening processes in the apple and the
relation of time of gathering in the chemical
changes in cold storage, Ann. Bot. 46:407-459. 1932
___ Physiological studies in plant nutrition:
The role of fructosans in the carbohydrate metabolism
of the barley plant. Materials used and method of
sugar analysis employed. Ann. Bot. N.S. 2:183-202.
1938.
__Physiological studies in plant nutrition:
The role of fructosans in the carbohydrate metabolism
in the barley plant. Ann. Bot, N.S. 2:403-435. 1938
Fructosans in the monocotyledons: A review
New Phytologist 39:185-219. 1940.
___ Physiological studies in plant nutrition:
~ Experiments with barley on defoliation and shading of
the ear in relation to sugar metabolism. Ann. Bot.
N.S. 6:487-531. 1942.
and BARTER, A.M. A fructose anhydride from
the leaves of the barley plant. Biochem. Jour. 29:
2689. 1935.
and DATTA, C. Sugar metabolism in the bar-
ley stem"in relation to ear development. Ann. Bot.
N.S. 8(32):363-384. 1944.
_ ^ and MUKERJEE, B.N. Physiological studies
in plant nutrition: Carbohydrate changes in the
several organs of the barley plant during growth,
with special reference to the development and ripen¬
ing of the ear. Ann. Bot. N.S. 6:1-41, 1942.
BARNELL, H.R. Seasonal changes in the carbohydrates of
the wheat plant. New Phytologist 35:229-266. 1936.
Distribution of the carbohydrates between
component parts of the wheat plant at various times
of the season. New Phytologist 37:85-112. 1938.
CURTIS, O.T. The food content of forage crops as in¬
fluenced by the time of day at which they are cut.
Jour. Am. Soc. Agron. 36:401. 1944.
' * o
loohiedo afiit at \ i.clLovoobo tv to n..cl$rd,3*i
* . •. . }
; .O.w;-
■ 11 : .. a t . il , o
... r : ; ' : . : ... To
* ■ . ' ' - : '
I ft 0 . .
■\ . . 70 ,...d 0 ^...r \xi£c.o$ Oi.:Tl
:anc . . vm*
v . i ■ r; . I ; 7 T‘ 00 '“
i ■' ■ ■ ■ . ..
.' 0 I'i - 0ii
, . *j
. 01 ..' - ; S: 0 \ ..
*M* . _ , . . .
■ , • ;o 1 .OcTT
«0 « - _ .
*
,* • •' c r : : \ - * ■
, . • \ ^_
:
.. . ZJJ
~aeql r< ■ "$ - c si o . 1 J ■ . Io.
, - j ■ 4 • 0. . , . • . * .. '
; . . ,
US’-). Oi: : <;3ii' -'I.';- v'odiuso Cf to i.QSOOC ' _^
•• jriBj ■
; l
. J', . ' • . *
»
69
12. GREGORY, F.G. Mineral nutrition of plants. Ann. Rev.
Biochem. 6:577. 1937.
13. HAWORTH, W.N., HIRST, E.L., and LYME, R.R. A water-
soluble polysaccharide from barley leaves. Biochem.
lour. 31:786. 1937.
14. NORMAN, G.A. The composition of forage crops. Biochem.
lour. 30:1354-1362. 1936.
15. REIGH, W.S. Separation of glucose and fructose.
Biochem, lour. 33:1000. 1939.
16. RICHARDS, F.I. Physiological studies in plant nutrition:
The relation of respiration rate to the carbohydrate
and nitrogen metabolism of the barley leaf as deter¬
mined by phosphorus and potassium supply. Ann.
Bot. N.S. 2:491-534. 1938.
17. RUSSELL, R.S. The effect of mineral deficiency on the
fructosan metabolism of the barley plant, Ann. Bot.
N.S. 2:865-882. 1938.
18. SHAFFER, S0M0GYI. Gopper-iodometric reagents for sugar
determination. lour. Biol. Chem. 100:695. 1933.
19. VAN DER PLANK, I.E. The estimation of sugars in the leaf
of the mangold, Biochem. Jour. 30:457-483. 1936.
20. WILLARD, G.J. Afternoon vs. morning cutting of alfalfa.
(Also notes by WOODWARD, T.E., SHEPHERD, J.B.,
TYSDALE, W.H. and CURTIS, O.T.). Jour. Am. Soc.
Agron. 36:937-952. 1944.
21. YEMM, E.W. Methods for determination of carbohydrates
in leaves, Proc. Royal Soc. of London, Series B.
117:483-504. 1935.
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